外文资料 水合物~~~~~
【论文名】[Ph.D.thesis].Seismic characterization of methane hydrate structures<<甲烷水合物地震特征结构>>
【作者】Christine Ecker
【单位】Standford University,2001.
【文件格式】PDF
【页数】144
【内容简介】Methane Hydrates
【附件个数】2
【威望要求】
Bottom simulating reflectors(BSR)seem to be associated with the base of the stability zone
of methane hydrates.These methane hydrates represent a potential future energy resource
and might have a strong“greenhouse”effect on global climate.In this dissertation I integrate
seismic and rock-physics to analyze seismic data from the Blake Outer Ridge,offshore Florida.
I infer the cause of the BSR visible in the data and estimate the amount of hydrate present in
the sediment structure.
Using stacking velocity analysis,2-D impedance inversion and AVO analysis,I show that
the Blake Outer Ridge BSR is caused by hydrate-bearing sediments overlying gas-saturated
sediments.Furthermore,the analysis suggests that a flat reflector beneath the BSR represents
the transition of gas-to brine-saturated sediments.Using the interval velocity obtained from
the RMS velocities in conjunction with physical rock models,I provide a theoretical tool to
quantify the amount of hydrate present.I examine three micromechanical models of hydrate
formation:(A)hydrate is part of the pore fluid,(B)hydrate becomes part of the solid frame,
and(C)hydrate cements grain contacts together.Model A predicts maximum hydrate sat-
uration between 20%and 26%,model B saturations between 15%and 20%,and model C
saturations of less than 1%.Subsequently,I analyze the stability of these estimates to errors
in interval velocity.Such errors can cause the estimations to vary as much as±14%,indi-
cating that accurate velocity determination is crucial.The saturation estimation technique is
furthermore validated by using known sonic velocities and porosities from two wells at the
Blake Ridge.Finally,in order to differentiate between the different models,I use forward
1-D modeling and AVO analysis.Both models A and B can qualitatively reproduce the BSR
amplitude trend observed in the seismic data,however,they cannot be distinguished by means
ivof their seismic responses.
This dissertation provides a tool for characterizing hydrate properties and estimating the
amount of hydrate in the pore space.Although the study has been applied to data at the Blake
Ridge,it could easily be transfered to a different geographic region.
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